THE SWITCH 1 PM machines for propulsion Permanent magnet motors offer an array of advantages when utilized for propulsion power WORDS: JUSSI PURANEN D iesel-electric propulsion systems have become the preferred choice for many types of vessels – especially cruise ships. Compared with traditional diesel-mechanical systems, they offer clear benefits: lower fuel consumption at speeds below design speed, increased redundancy and excellent torque-speed characteristics. For vessels with high power demands during cargo handling operations, they also reduce the need for installed power capacity. Taking diesel-electric propulsion one step further, permanent magnet (PM) machines as propulsion motors deliver even greater efficiency. As they require no external energy for magnetization, they help minimize both fuel consumption and emissions. PM machines also offer lower maintenance requirements and higher reliability, and their compact design frees up valuable space for cargo. The Switch’s marine PM machines have already accumulated several million hours of reliable operation at sea, earning consistently excellent feedback from customers. Basic concept In a diesel-electric propulsion system, the primary power is generated by a dedicated power station consisting of four to eight diesel generator sets. The electric power produced by these gensets is fed through transformers and the main switchboard to the propulsion drives, where frequency converters control the speed of the propulsion motors that run the propellers. Although this setup is more complex and typically more costly than conventional diesel-mechanical propulsion, it offers greater design and operational flexibility. It also offers fuel savings for many types of vessels, 2 42 // April-May 2025 // ElectricHybridMarineTechnology.com
Electric & Hybrid Marine Technology International April - May 2025: Page 42
